Production of products from biomass

ABSTRACT

The processes disclosed herein include saccharifying cellulosic and/or lignocellulosic biomass and fermenting the sugars to produce a sugar alcohol.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.15/938,281, filed Mar. 28, 2018, which is a continuation of U.S.application Ser. No. 14/016,481, filed Sep. 3, 2013, now U.S. Pat. No.9,963,727, issued on May 8, 2018, which is a continuation ofPCT/US2012/071083 filed Dec. 20, 2012, which claimed priority to U.S.Provisional Application No. 61/579,576, filed on Dec. 22, 2011. Theentirety of the disclosure in the above applications are incorporatedherein by reference.

FIELD OF THE INVENTION

The invention pertains to the production of products, e.g., sugaralcohols, e.g., such as erythritol.

BACKGROUND

As demand for petroleum increases, so too does interest in renewablefeedstocks for manufacturing biofuels and biochemicals. The use oflignocellulosic biomass as a feedstock for such manufacturing processeshas been studied since the 1970s. Lignocellulosic biomass is attractivebecause it is abundant, renewable, domestically produced, and does notcompete with food industry uses.

Many potential lignocellulosic feedstocks are available today, includingagricultural residues, woody biomass, municipal waste, oilseeds/cakesand sea weeds, to name a few. At present these materials are either usedas animal feed, biocompost materials, are burned in a cogenerationfacility or are landfilled.

Lignocellulosic biomass is recalcitrant to degradation as the plant cellwalls have a structure that is rigid and compact. The structurecomprises crystalline cellulose fibrils embedded in a hemicellulosematrix, surrounded by lignin. This compact matrix is difficult to accessby enzymes and other chemical, biochemical and biological processes.Cellulosic biomass materials (e.g., biomass material from whichsubstantially all the lignin has been removed) can be more accessible toenzymes and other conversion processes, but even so, naturally-occurringcellulosic materials often have low yields (relative to theoreticalyields) when contacted with hydrolyzing enzymes. Lignocellulosic biomassis even more recalcitrant to enzyme attack. Furthermore, each type oflignocellulosic biomass has its own specific composition of cellulose,hemicellulose and lignin.

While a number of methods have been tried to extract structuralcarbohydrates from lignocellulosic biomass, they are either tooexpensive, produce too low a yield, leave undesirable chemicals in theresulting product, or simply degrade the sugars.

Saccharides from renewable biomass sources could become the basis of thechemical and fuels industries by replacing, supplementing orsubstituting petroleum and other fossil feedstocks. However, techniquesneed to be developed that will make these monosaccharides available inlarge quantities and at acceptable purities and prices.

SUMMARY OF THE INVENTION

A method is provided for making a sugar alcohol from a cellulosic orlignocellulosic biomass that contains one or more sugars that includescombining the cellulosic or lignocellulosic biomass with a microorganismthat is capable of converting at least one of the sugars to a sugaralcohol, and maintaining the microorganism-biomass combination underconditions that enable the microorganism to convert at least one of thesugars to the sugar alcohol. In some implementations, the methodincludes: providing a cellulosic or lignocellulosic biomass, wherein thecellulosic or lignocellulosic biomass contains one or more sugars;providing a microorganism that is capable of converting at least one ofthe sugars to a sugar alcohol; combining the cellulosic orlignocellulosic biomass with the microorganism, thereby producing amicroorganism-biomass combination; and maintaining themicroorganism-biomass combination under conditions that enable themicroorganism to convert at least one of the sugars to a sugar alcohol;thereby making a sugar alcohol from a cellulosic or lignocellulosicbiomass. The cellulosic or lignocellulosic biomass can be saccharified.

Any of the methods provided herein can include reducing therecalcitrance of the cellulosic or lignocellulosic biomass tosaccharification prior to combining it with the microorganism. Therecalcitrance can be reduced by a treatment method selected from thegroup consisting of: bombardment with electrons, sonication, oxidation,pyrolysis, steam explosion, chemical treatment, mechanical treatment,and freeze grinding. The treatment method can be bombardment withelectrons.

Any of the methods provided herein can also include mechanicallytreating the cellulosic or lignocellulosic biomass to reduce its bulkdensity and/or increase its surface area. For instance, the cellulosicor lignocellulosic biomass can be comminuted, for instance, it can bedry milled, or it can be wet milled.

In any of the methods provided herein, the biomass can be saccharifiedwith one or more cellulases. Any of the methods can also includeseparating one or more sugars prior to combining the cellulosic orlignocellulosic biomass with the microorganism, or the methods caninclude concentrating the one or more sugars prior to combining thecellulosic or lignocellulosic biomass with the microorganism. Themethods can also include both concentrating and separating one or moresugars prior to combining the cellulosic or lignocellulosic biomass withthe microorganism. The saccharified biomass can be adjusted to have aninitial glucose concentration of at least 5 wt %. The saccharifiedbiomass can also be purified, for instance, by the removal of metalions.

Any of the methods disclosed herein can also include culturing themicroorganism in a cell growth phase before combining the cellulosic orlignocellulosic biomass with the microorganism.

In any of the methods provided herein, the sugar alcohol can be glycol,glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol,sorbitol, galactitol, iditol, inositol, volemitol, isomalt, maltitol,lactitol, maltotriitol, maltotetraitol, or polyglycitol.

The microorganism can be Moniliella pollinis, Moniliella megachiliensis,Yarrowia lipolytica, Aureobasidium sp., Trichosporonoides sp.,Trigonopsis variabilis, Trichosporon sp., Moniliellaacetoabutans,Typhula variabilis, Candida magnoliae, Ustilaginomycetes, Pseudozymatsukubaensis; yeast species of genera Zygosaccharomyces, Debaryomyces,Hansenula and Pichia, or fungi of the dematioid genus Torula. Themicroorganism can be a species of Moniliella, such as M. pollinis, forinstance, strain CBS 461.67, or M. megachiliensis, strain CBS 567.85.

In any of the methods provided herein, the cellulosic or lignocellulosicbiomass can be: paper, paper products, paper waste, paper pulp,pigmented papers, loaded papers, coated papers, filled papers,magazines, printed matter, printer paper, polycoated paper, card stock,cardboard, paperboard, cotton, wood, particle board, forestry wastes,sawdust, aspen wood, wood chips, grasses, switchgrass, miscanthus, cordgrass, reed canary grass, grain residues, rice hulls, oat hulls, wheatchaff, barley hulls, agricultural waste, silage, canola straw, wheatstraw, barley straw, oat straw, rice straw, jute, hemp, flax, bamboo,sisal, abaca, corn cobs, corn stover, soybean stover, corn fiber,alfalfa, hay, coconut hair, sugar processing residues, bagasse, beetpulp, agave bagasse, algae, seaweed, manure, sewage, offal, arracacha,buckwheat, banana, barley, cassava, kudzu, oca, sago, sorghum, potato,sweet potato, taro, yams, beans, favas, lentils, peas, or mixtures ofany of these.

It should be understood that this invention is not limited to theembodiments disclosed in this Summary, and it is intended to covermodifications that are within the spirit and scope of the invention, asdefined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing will be apparent from the following more particulardescription of example embodiments of the invention, as illustrated inthe accompanying drawings in which like reference characters refer tothe same parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingembodiments of the present invention.

FIG. 1 is a diagram illustrating the enzymatic hydrolysis of celluloseto glucose. Cellulosic substrate (A) is converted by endocellulase (i)to cellulose (B), which is converted by exocellulase (ii) to cellobiose(C), which is converted to glucose (D) by cellobiase (beta-glucosidase)(iii).

FIG. 2 is a flow diagram illustrating conversion of a biomass feedstockto one or more products. Feedstock is physically pretreated (e.g., toreduce its size) (200), optionally treated to reduce its recalcitrance(210), saccharified to form a sugar solution (220), the solution istransported (230) to a manufacturing plant (e.g., by pipeline, railcar)(or if saccharification is performed en route, the feedstock, enzyme andwater is transported), the saccharified feedstock is bio-processed toproduce a desired product (e.g., alcohol) (240), and the product can beprocessed further, e.g., by distillation, to produce a final product(250). Treatment for recalcitrance can be modified by measuring lignincontent (201) and setting or adjusting process parameters (205).Saccharifying the feedstock (220) can be modified by mixing thefeedstock with medium and the enzyme (221).

DETAILED DESCRIPTION

This invention relates to methods of processing biomass feedstockmaterials (e.g., biomass materials or biomass-derived materials such ascellulosic and lignocellulosic materials) to obtain sugar alcohols suchas erythritol ((2R,3S)-butane-1,2,3,4-tetraol), or isomers, or mixturesthereof.

In some instances, the recalcitrance of the feedstock is reduced priorto saccharification. In some cases, reducing the recalcitrance of thefeedstock includes treating the feedstock. The treatment can, forexample, be radiation, e.g., electron beam radiation, sonication,pyrolysis, oxidation, steam explosion, chemical treatment, orcombinations of any of these.

In some implementations, the method also includes mechanically treatingthe feedstock before and/or after reducing its recalcitrance. Mechanicaltreatments include, for example, cutting, milling, e.g., hammermilling,pressing, grinding, shearing and chopping. Mechanical treatment mayreduce the bulk density of the feedstock and/or increase the surfacearea of the feedstock. In some embodiments, after mechanical treatmentthe material has a bulk density of less than 0.75 g/cm3, e.g., less thanabout 0.7, 0.65, 0.60, 0.50, 0.35, 0.25, 0.20, 0.15, 0.10, 0.05, orless, e.g., less than 0.025 g/cm3. Bulk density is determined using ASTMD1895B. Under some circumstances, mechanical treatments can remove orreduce recalcitrance.

In one aspect, the invention features a method that includes contactinga sugar, produced by saccharifying a cellulosic or lignocellulosicfeedstock with a microorganism to produce a product, such as a sugaralcohol e.g., erythritol. Other products include, for example, citricacid, lysine and glutamic acid.

In some implementations, the microorganism includes Moniliella pollinis,Yarrowia lipolytica, Aureobasidium sp., Trichosporonoides sp.,Trigonopsis variabilis, Trichosporon sp., Moniliellaacetoabutans,Typhula variabilis, Candida magnoliae, Ustilaginomycetes, Pseudozymatsukubaensis; yeast species of genera Zygosaccharomyces, Debaryomyces,Hansenula and Pichia; and fungi of the dematioid genus Torula.

In some implementations, the contacting step includes a dual stageprocess, comprising a cell growth step and a fermentation step.Optionally, the fermentation is performed using a glucose solutionhaving an initial glucose concentration of at least 5 wt. % at the startof the fermentation. Furthermore, the glucose solution can be dilutedafter fermentation has begun.

As shown in FIG. 1, for example, during saccharification a cellulosicsubstrate (A) is initially hydrolyzed by endoglucanases (i) at randomlocations producing oligomeric intermediates (e.g., cellulose) (B).These intermediates are then substrates for exo-splitting glucanases(ii) such as cellobiohydrolase to produce cellobiose from the ends ofthe cellulose polymer. Cellobiose is a water-soluble 1,4-linked dimer ofglucose. Finally cellobiase (iii) cleaves cellobiose (C) to yieldglucose (D). Therefore, the endoglucanases are particularly effective inattacking the crystalline portions of cellulose and increasing theeffectiveness of exocellulases to produce cellobiose, which thenrequires the specificity of the cellobiose to produce glucose.Therefore, it is evident that depending on the nature and structure ofthe cellulosic substrate, the amount and type of the three differentenzymes may need to be modified.

In some implementations, the enzyme is produced by a fungus, e.g., bystrains of the cellulolytic filamentous fungus Trichoderma reesei. Forexample, high-yielding cellulase mutants of Trichoderma reesei may beused, e.g., RUT-NG14, PC3-7, QM9414 and/or Rut-C30. Such strains aredescribed, for example, in “Selective Screening Methods for theIsolation of High Yielding Cellulase Mutants of Trichoderma reesei,”Montenecourt, B. S. and Everleigh, D. E., Adv. Chem. Ser. 181, 289-301(1979), the full disclosure of which is incorporated herein byreference. Other cellulase-producing microorganisms may also be used.

As shown in FIG. 2, a process for manufacturing a sugar alcohol caninclude, for example, optionally mechanically treating a feedstock,e.g., to reduce its size (200), before and/or after this treatment,optionally treating the feedstock with another physical treatment tofurther reduce its recalcitrance (210), then saccharifying thefeedstock, using the enzyme complex, to form a sugar solution (220).Optionally, the method may also include transporting, e.g., by pipeline,railcar, truck or barge, the solution (or the feedstock, enzyme andwater, if saccharification is performed en route) to a manufacturingplant (230). In some cases the saccharified feedstock is furtherbioprocessed (e.g., fermented) to produce a desired product e.g.,alcohol (240). This resulting product may in some implementations beprocessed further, e.g., by distillation (250), to produce a finalproduct. One method of reducing the recalcitrance of the feedstock is byelectron bombardment of the feedstock. If desired, the steps ofmeasuring lignin content of the feedstock (201) and setting or adjustingprocess parameters based on this measurement (205) can be performed atvarious stages of the process, as described in U.S. Pat. App. Pub.2010/0203495 A1 by Medoff and Masterman, published Aug. 12, 2010, thecomplete disclosure of which is incorporated herein by reference.Saccharifying the feedstock (220) can also be modified by mixing thefeedstock with medium and the enzyme (221).

In some cases, the feedstock is boiled, steeped, or cooked in hot waterprior to saccharification, as described in U.S. Ser. No. 13/276,192,filed Oct. 18, 2011.

The processes described above can be partially or completely performedin a tank (e.g., a tank having a volume of at least 4000, 40,000, or500,000 L) in a manufacturing plant, and/or can be partially orcompletely performed in transit, e.g., in a rail car, tanker truck, orin a supertanker or the hold of a ship. Mobile fermenters can beutilized, as described in U.S. Pat. App. Pub. 2010/0064746 A1, publishedon Mar. 18, 2010, the entire disclosure of which is incorporated byreference herein.

It is generally preferred that the tank and/or fermenter contents bemixed during all or part of the process, e.g., using jet mixing asdescribed in U.S. Pat. App. Pub. 2010/0297705 A1, filed May 18, 2010 andpublished on Nov. 25, 2012, U.S. Pat. App. Pub. 2012/0100572 A1, filedNov. 10, 2011 and published on Apr. 26, 2012, U.S. Pat. App. Pub.2012/0091035 A1, filed Nov. 10, 2011 and published on Apr. 19, 2012, thefull disclosures of which are incorporated by reference herein.

The addition of additives such as e.g., surfactants or nutrients, canenhance the rate of saccharification. Examples of surfactants includenon-ionic surfactants, such as a Tween® 20 or Tween® 80 polyethyleneglycol surfactants, ionic surfactants, or amphoteric surfactants.

One or more useful products may be produced. For example glycol,glycerol, erythritol, threitol, arabitol, xylitol, ribitol, mannitol,sorbitol, galactitol, iditol, inositol, volemitol, isomalt, maltitol,lactitol, maltotriitol, maltotetraitol, and polyglycitol can be producedby fermentation. In addition, butyric acid, gluconic acid and citricacid also can be produced.

In some embodiments, polyols can be made by fermentation, includingmonomeric polyols such as glycerin, pentaerythritol, ethylene glycol,and sucrose. These can be built up into polymeric polyols such aspolyether polyols.

In some embodiments, the optionally mechanically and/or physicallytreated feedstock can be combined with an enzyme complex forsaccharification and is also combined with an organism that ferments atleast a part of the released sugars to a sugar alcohol. The sugaralcohol is then isolated from other products and non-fermented materialsuch as solids, un-fermentable sugars and cellular debris.

The optionally mechanically and/or physically treated feedstock can alsobe combined with an enzyme complex for saccharification and after thesaccharification is at least partially completed, the mixture iscombined with an organism that produces sugar alcohols. The conditionsfor saccharification (e.g., temperature, agitation, aeration) can bedifferent than the conditions for fermentation. The optimum pH forfermentation is generally from about pH 4 to 6. Typical fermentationtimes are about 24 to 120 hours with temperatures in the range of 25° C.to 40° C., e.g., 25° C. to 30° C. Fermentation is typically done withaeration using a sparging tube and an air and/or oxygen supply tomaintain the dissolved oxygen level above about 10% (e.g., above about20%). The saccharification and fermentation can be in the same ordifferent reactor/vessel. The sugar alcohol is then isolated. Asdiscussed above, the fermentation can be performed during atransportation process.

Generally, a high initial sugar concentration at the start offermentation favors the production of sugar alcohols. Accordingly, thesaccharified feedstock solution can be concentrated prior to combinationwith the organism that produces sugar alcohols to increase the glucoselevel of the solution. Concentration can be done by any desiredtechnique. For example, concentration can be by heating, cooling,centrifugation, reverse osmosis, chromatography, precipitation,crystallization, evaporation, adsorption and combinations thereof.Preferably concentration is done by evaporation of at least a portion ofthe liquids from the saccharified feedstock. Concentration is preferablydone to increase the glucose content to greater than about 5 wt %, e.g.,greater than 10 wt. %, greater than 15 wt. %, greater than 20 wt. %,greater than 30 wt. %, greater than 40 wt. % or even greater than 50 wt.%. The product from the fermentation is then isolated.

The saccharified feedstock can also be purified before or afterconcentration. Purification is preferably done to increase the glucosecontent to greater than about 50 wt. % of all components other thanwater (e.g., greater than about 60 wt. %, greater than about 70 wt. %,greater than about 80 wt. %, greater than about 90 wt. % and evengreater than about 99 wt. %). Purification can be done by any desiredtechnique, for example, by heating, cooling, centrifugation, reverseosmosis, chromatography, precipitation, crystallization, evaporation,adsorption or combinations of any of these.

In some implementations the fermentation is dual-stage, with a cellgrowth phase and a product production phase. In the growth phase,conditions are selected to optimize cell growth, while in the productionphase conditions are selected to optimize production of the desiredfermentation products. Generally, low sugar levels (e.g., between 0.1and 10 wt. %, between 0.2 and 5 wt. %) in the growth medium favor cellgrowth, and high sugar levels (e.g., greater than 5 wt. %, greater thanabout 10 wt. %, greater than 20 wt. %, greater than 30 wt. %, greaterthan 40 wt. %) in the fermentation medium favor product production.Other conditions can be optionally modified in each stage, for example,temperature, agitation, sugar levels, nutrients and/or pH. Monitoring ofconditions in each stage can be done to optimize the process. Forexample, growth can be monitored to achieve an optimum density, e.g.,about 50 g/L (e.g., greater than 60 g/L, greater than 70 g/L or greaterthan about 75 g/L), and a concentrated saccharified solution can beadded to trigger the onset of product formation. Optionally, the processcan be optimized, for example, by monitoring and adjusting the pH oroxygenation level with probes and automatic feeding to control cellgrowth and product formation. Furthermore, other nutrients can becontrolled and monitored to optimize the process (e.g., amino acids,vitamins, metal ions, yeast extract, vegetable extracts, peptones,carbon sources and proteins).

Dual-stage fermentations are described in Biotechnological production oferythritol and its applications, Hee-Jung Moon et al., Appl. Microbiol.Biotechnol. (2010) 86:1017-1025. While generally a high initialconcentration of glucose at the start of the fermentation favorserythritol production, if this high concentration is maintained too longit may be detrimental to the organism. A high initial glucoseconcentration can be achieved by concentrating glucose during or aftersaccharification as discussed above. After an initial fermentation timeto allow the start of fermentation, the fermentation media is dilutedwith a suitable diluent so that the glucose level is brought below about60 wt. % (e.g., below about 50 wt. %, below about 40 wt. %). The diluentcan be water or water with additional components such as amino acids,vitamins, metal ions, yeast extract, vegetable extracts, peptones,carbon sources and proteins.

Biomass Materials

As used herein, the term “biomass materials” includes lignocellulosic,cellulosic, starchy, and microbial materials.

Lignocellulosic materials include, but are not limited to, wood,particle board, forestry wastes (e.g., sawdust, aspen wood, wood chips),grasses, (e.g., switchgrass, miscanthus, cord grass, reed canary grass),grain residues, (e.g., rice hulls, oat hulls, wheat chaff, barleyhulls), agricultural waste (e.g., silage, canola straw, wheat straw,barley straw, oat straw, rice straw, jute, hemp, flax, bamboo, sisal,abaca, corn cobs, corn stover, soybean stover, corn fiber, alfalfa, hay,coconut hair), sugar processing residues (e.g., bagasse, beet pulp,agave bagasse), algae, seaweed, manure, sewage, and mixtures of any ofthese.

In some cases, the lignocellulosic material includes corncobs. Ground orhammermilled corncobs can be spread in a layer of relatively uniformthickness for irradiation, and after irradiation are easy to disperse inthe medium for further processing. To facilitate harvest and collection,in some cases the entire corn plant is used, including the corn stalk,corn kernels, and in some cases even the root system of the plant.

Advantageously, no additional nutrients (other than a nitrogen source,e.g., urea or ammonia) are required during fermentation of corncobs orcellulosic or lignocellulosic materials containing significant amountsof corncobs.

Corncobs, before and after comminution, are also easier to convey anddisperse, and have a lesser tendency to form explosive mixtures in airthan other cellulosic or lignocellulosic materials such as hay andgrasses.

Cellulosic materials include, for example, paper, paper products, paperwaste, paper pulp, pigmented papers, loaded papers, coated papers,filled papers, magazines, printed matter (e.g., books, catalogs,manuals, labels, calendars, greeting cards, brochures, prospectuses),newsprint, printer paper, polycoated paper, card stock, cardboard,paperboard, materials having a high α-cellulose content such as cotton,and mixtures of any of these. For example paper products as described inU.S. application Ser. No. 13/396,365 filed Feb. 14, 2012 (publicationNo. 2013-0052687-A1, published Feb. 28, 2013), the full disclosure ofwhich is incorporated herein by reference.

Cellulosic materials can also include lignocellulosic materials whichhave been de-lignified.

Starchy materials include starch itself, e.g., corn starch, wheatstarch, potato starch or rice starch, a derivative of starch, or amaterial that includes starch, such as an edible food product or a crop.For example, the starchy material can be arracacha, buckwheat, banana,barley, cassava, kudzu, oca, sago, sorghum, regular household potatoes,sweet potato, taro, yams, or one or more beans, such as favas, lentilsor peas. Blends of any two or more starchy materials are also starchymaterials. Mixtures of starchy, cellulosic and or lignocellulosicmaterials can also be used. For example, a biomass can be an entireplant, a part of a plant or different parts of a plant, e.g., a wheatplant, cotton plant, a corn plant, rice plant or a tree. The starchymaterials can be treated by any of the methods described herein.

Microbial materials include, but are not limited to, any naturallyoccurring or genetically modified microorganism or organism thatcontains or is capable of providing a source of carbohydrates (e.g.,cellulose), for example, protists, e.g., animal protists (e.g., protozoasuch as flagellates, amoeboids, ciliates, and sporozoa) and plantprotists (e.g., algae such alveolates, chlorarachniophytes,cryptomonads, euglenids, glaucophytes, haptophytes, red algae,stramenopiles, and viridaeplantae). Other examples include seaweed,plankton (e.g., macroplankton, mesoplankton, microplankton,nanoplankton, picoplankton, and femptoplankton), phytoplankton, bacteria(e.g., gram positive bacteria, gram negative bacteria, andextremophiles), yeast and/or mixtures of these. In some instances,microbial biomass can be obtained from natural sources, e.g., the ocean,lakes, bodies of water, e.g., salt water or fresh water, or on land.Alternatively or in addition, microbial biomass can be obtained fromculture systems, e.g., large scale dry and wet culture and fermentationsystems.

The biomass material can also include offal, and similar sources ofmaterial.

In other embodiments, the biomass materials, such as cellulosic, starchyand lignocellulosic feedstock materials, can be obtained from transgenicmicroorganisms and plants that have been modified with respect to a wildtype variety. Such modifications may be, for example, through theiterative steps of selection and breeding to obtain desired traits in aplant. Furthermore, the plants can have had genetic material removed,modified, silenced and/or added with respect to the wild type variety.For example, genetically modified plants can be produced by recombinantDNA methods, where genetic modifications include introducing ormodifying specific genes from parental varieties, or, for example, byusing transgenic breeding wherein a specific gene or genes areintroduced to a plant from a different species of plant and/or bacteria.Another way to create genetic variation is through mutation breedingwherein new alleles are artificially created from endogenous genes. Theartificial genes can be created by a variety of ways including treatingthe plant or seeds with, for example, chemical mutagens (e.g., usingalkylating agents, epoxides, alkaloids, peroxides, formaldehyde),irradiation (e.g., X-rays, gamma rays, neutrons, beta particles, alphaparticles, protons, deuterons, UV radiation) and temperature shocking orother external stressing and subsequent selection techniques. Othermethods of providing modified genes is through error prone PCR and DNAshuffling followed by insertion of the desired modified DNA into thedesired plant or seed. Methods of introducing the desired geneticvariation in the seed or plant include, for example, the use of abacterial carrier, biolistics, calcium phosphate precipitation,electroporation, gene splicing, gene silencing, lipofection,microinjection and viral carriers. Additional genetically modifiedmaterials have been described in U.S. application Ser. No. 13/396,369filed Feb. 14, 2012 (Publication No. 2013-0052682 published Feb. 28,2013) the full disclosure of which is incorporated herein by reference.

Any of the methods described herein can be practiced with mixtures ofany biomass materials described herein.

Biomass Material Preparation—Mechanical Treatments

The biomass can be in a dry form, for example with less than about 35%moisture content (e.g., less than about 20%, less than about 15%, lessthan about 10% less than about 5%, less than about 4%, less than about3%, less than about 2% or even less than about 1%). The biomass can alsobe delivered in a wet state, for example as a wet solid, a slurry or asuspension with at least about 10 wt % solids (e.g., at least about 20wt. %, at least about 30 wt. %, at least about 40 wt. %, at least about50 wt. %, at least about 60 wt. %, at least about 70 wt. %).

The processes disclosed herein can utilize low bulk density materials,for example cellulosic or lignocellulosic feedstocks that have beenphysically pretreated to have a bulk density of less than about 0.75g/cm³, e.g., less than about 0.7, 0.65, 0.60, 0.50, 0.35, 0.25, 0.20,0.15, 0.10, 0.05 or less, e.g., less than about 0.025 g/cm³. Bulkdensity is determined using ASTM D1895B. Briefly, the method involvesfilling a measuring cylinder of known volume with a sample and obtaininga weight of the sample. The bulk density is calculated by dividing theweight of the sample in grams by the known volume of the cylinder incubic centimeters. If desired, low bulk density materials can bedensified, for example, by methods described in U.S. Pat. No. 7,971,809to Medoff, the full disclosure of which is hereby incorporated byreference.

In some cases, the pre-treatment processing includes screening of thebiomass material. Screening can be through a mesh or perforated platewith a desired opening size, for example, less than about 6.35 mm (¼inch, 0.25 inch), (e.g., less than about 3.18 mm (⅛ inch, 0.125 inch),less than about 1.59 mm ( 1/16 inch, 0.0625 inch), is less than about0.79 mm ( 1/32 inch, 0.03125 inch), e.g., less than about 0.51 mm ( 1/50inch, 0.02000 inch), less than about 0.40 mm ( 1/64 inch, 0.015625inch), less than about 0.23 mm (0.009 inch), less than about 0.20 mm (1/128 inch, 0.0078125 inch), less than about 0.18 mm (0.007 inch), lessthan about 0.13 mm (0.005 inch), or even less than about 0.10 mm ( 1/256inch, 0.00390625 inch)). In one configuration the desired biomass fallsthrough the perforations or screen and thus biomass larger than theperforations or screen are not irradiated. These larger materials can bere-processed, for example by comminuting, or they can simply be removedfrom processing. In another configuration material that is larger thanthe perforations is irradiated and the smaller material is removed bythe screening process or recycled. In this kind of a configuration, theconveyor itself (for example a part of the conveyor) can be perforatedor made with a mesh. For example, in one particular embodiment thebiomass material may be wet and the perforations or mesh allow water todrain away from the biomass before irradiation.

Screening of material can also be by a manual method, for example by anoperator or mechanoid (e.g., a robot equipped with a color, reflectivityor other sensor) that removes unwanted material. Screening can also beby magnetic screening wherein a magnet is disposed near the conveyedmaterial and the magnetic material is removed magnetically.

Optional pre-treatment processing can include heating the material. Forexample a portion of the conveyor can be sent through a heated zone. Theheated zone can be created, for example, by IR radiation, microwaves,combustion (e.g., gas, coal, oil, biomass), resistive heating and/orinductive coils. The heat can be applied from at least one side or morethan one side, can be continuous or periodic and can be for only aportion of the material or all the material. For example, a portion ofthe conveying trough can be heated by use of a heating jacket. Heatingcan be, for example, for the purpose of drying the material. In the caseof drying the material, this can also be facilitated, with or withoutheating, by the movement of a gas (e.g., air, oxygen, nitrogen, He, CO₂,Argon) over and/or through the biomass as it is being conveyed.

Optionally, pre-treatment processing can include cooling the material.Cooling material is described in U.S. Pat. No. 7,900,857 to Medoff, thedisclosure of which in incorporated herein by reference. For example,cooling can be by supplying a cooling fluid, for example water (e.g.,with glycerol), or nitrogen (e.g., liquid nitrogen) to the bottom of theconveying trough. Alternatively, a cooling gas, for example, chillednitrogen can be blown over the biomass materials or under the conveyingsystem.

Another optional pre-treatment processing method can include adding amaterial to the biomass. The additional material can be added by, forexample, by showering, sprinkling and or pouring the material onto thebiomass as it is conveyed. Materials that can be added include, forexample, metals, ceramics and/or ions as described in U.S. Pat. App.Pub. 2010/0105119 A1 published Apr. 29, 2010 (filed Oct. 26, 2009) andU.S. Pat. App. Pub. 2010/0159569 A1 published Jun. 24, 2010 (filed Dec.16, 2009), the entire disclosures of which are incorporated herein byreference. Optional materials that can be added include acids and bases.Other materials that can be added are oxidants (e.g., peroxides,chlorates), polymers, polymerizable monomers (e.g., containingunsaturated bonds), water, catalysts, enzymes and/or organisms.Materials can be added, for example, in pure form, as a solution in asolvent (e.g., water or an organic solvent) and/or as a solution. Insome cases the solvent is volatile and can be made to evaporate e.g., byheating and/or blowing gas as previously described. The added materialmay form a uniform coating on the biomass or be a homogeneous mixture ofdifferent components (e.g., biomass and additional material). The addedmaterial can modulate the subsequent irradiation step by increasing theefficiency of the irradiation, damping the irradiation or changing theeffect of the irradiation (e.g., from electron beams to X-rays or heat).The method may have no impact on the irradiation but may be useful forfurther downstream processing. The added material may help in conveyingthe material, for example, by lowering dust levels.

Biomass can be delivered to the conveyor by a belt conveyor, a pneumaticconveyor, a screw conveyor, a hopper, a pipe, manually or by acombination of these. The biomass can, for example, be dropped, pouredand/or placed onto the conveyor by any of these methods. In someembodiments the material is delivered to the conveyor using an enclosedmaterial distribution system to help maintain a low oxygen atmosphereand/or control dust and fines. Lofted or air suspended biomass fines anddust are undesirable because these can form an explosion hazard ordamage the window foils of an electron gun (if such a device is used fortreating the material).

The material can be leveled to form a uniform thickness between about0.0312 and 5 inches (e.g., between about 0.0625 and 2.000 inches,between about 0.125 and 1 inches, between about 0.125 and 0.5 inches,between about 0.3 and 0.9 inches, between about 0.2 and 0.5 inchesbetween about 0.25 and 1.0 inches, between about 0.25 and 0.5 inches,0.100+/−0.025 inches, 0.150+/−0.025 inches, 0.200+/−0.025 inches,0.250+/−0.025 inches, 0.300+/−0.025 inches, 0.350+/−0.025 inches,0.400+/−0.025 inches, 0.450+/−0.025 inches, 0.500+/−0.025 inches,0.550+/−0.025 inches, 0.600+/−0.025 inches, 0.700+/−0.025 inches,0.750+/−0.025 inches, 0.800+/−0.025 inches, 0.850+/−0.025 inches,0.900+/−0.025 inches, 0.900+/−0.025 inches.

Generally, it is preferred to convey the material as quickly as possiblethrough the electron beam to maximize throughput. For example thematerial can be conveyed at rates of at least 1 ft/min, e.g., at least 2ft/min, at least 3 ft/min, at least 4 ft/min, at least 5 ft/min, atleast 10 ft/min, at least 15 ft/min, 20, 25, 30, 35, 40, 45, 50 ft/min.The rate of conveying is related to the beam current, for example, for a¼ inch thick biomass and 100 mA, the conveyor can move at about 20ft/min to provide a useful irradiation dosage, at 50 mA the conveyor canmove at about 10 ft/min to provide approximately the same irradiationdosage.

After the biomass material has been conveyed through the radiation zone,optional post-treatment processing can be done. The optionalpost-treatment processing can, for example, be a process described withrespect to the pre-irradiation processing. For example, the biomass canbe screened, heated, cooled, and/or combined with additives. Uniquely topost-irradiation, quenching of the radicals can occur, for example,quenching of radicals by the addition of fluids or gases (e.g., oxygen,nitrous oxide, ammonia, liquids), using pressure, heat, and/or theaddition of radical scavengers. For example, the biomass can be conveyedout of the enclosed conveyor and exposed to a gas (e.g., oxygen) whereit is quenched, forming caboxylated groups. In one embodiment thebiomass is exposed during irradiation to the reactive gas or fluid.Quenching of biomass that has been irradiated is described in U.S. Pat.No. 8,083,906 to Medoff, the entire disclosure of which is incorporateherein by reference.

If desired, one or more mechanical treatments can be used in addition toirradiation to further reduce the recalcitrance of the biomass material.These processes can be applied before, during and/or after irradiation.

In some cases, the mechanical treatment may include an initialpreparation of the feedstock as received, e.g., size reduction ofmaterials, such as by comminution, e.g., cutting, grinding, shearing,pulverizing or chopping. For example, in some cases, loose feedstock(e.g., recycled paper, starchy materials, or switchgrass) is prepared byshearing or shredding. Mechanical treatment may reduce the bulk densityof the biomass material, increase the surface area of the biomassmaterial and/or decrease one or more dimensions of the biomass material.

Alternatively, or in addition, the feedstock material can first bephysically treated by one or more of the other physical treatmentmethods, e.g., chemical treatment, radiation, sonication, oxidation,pyrolysis or steam explosion, and then mechanically treated. Thissequence can be advantageous since materials treated by one or more ofthe other treatments, e.g., irradiation or pyrolysis, tend to be morebrittle and, therefore, it may be easier to further change the structureof the material by mechanical treatment. For example, a feedstockmaterial can be conveyed through ionizing radiation using a conveyor asdescribed herein and then mechanically treated. Chemical treatment canremove some or all of the lignin (for example chemical pulping) and canpartially or completely hydrolyze the material. The methods also can beused with pre-hydrolyzed material. The methods also can be used withmaterial that has not been pre-hydrolyzed. The methods can be used withmixtures of hydrolyzed and non-hydrolyzed materials, for example withabout 50% or more non-hydrolyzed material, with about 60% or morenon-hydrolyzed material, with about 70% or more non-hydrolyzed material,with about 80% or more non-hydrolyzed material or even with 90% or morenon-hydrolyzed material.

In addition to size reduction, which can be performed initially and/orlater in processing, mechanical treatment can also be advantageous for“opening up,” “stressing,” breaking or shattering the biomass materials,making the cellulose of the materials more susceptible to chain scissionand/or disruption of crystalline structure during the physicaltreatment.

Methods of mechanically treating the biomass material include, forexample, milling or grinding. Milling may be performed using, forexample, a mill, ball mill, colloid mill, conical or cone mill, diskmill, edge mill, Wiley mill, grist mill or other mill. Grinding may beperformed using, for example, a cutting/impact type grinder. Someexemplary grinders include stone grinders, pin grinders, coffeegrinders, and burr grinders. Grinding or milling may be provided, forexample, by a reciprocating pin or other element, as is the case in apin mill. Other mechanical treatment methods include mechanical ripping,tearing, shearing or chopping, other methods that apply pressure to thefibers, and air attrition milling. Suitable mechanical treatmentsfurther include any other technique that continues the disruption of theinternal structure of the material that was initiated by the previousprocessing steps.

Mechanical feed preparation systems can be configured to produce streamswith specific characteristics such as, for example, specific maximumsizes, specific length-to-width, or specific surface areas ratios.Physical preparation can increase the rate of reactions, improve themovement of material on a conveyor, improve the irradiation profile ofthe material, improve the radiation uniformity of the material, orreduce the processing time required by opening up the materials andmaking them more accessible to processes and/or reagents, such asreagents in a solution.

The bulk density of feedstocks can be controlled (e.g., increased). Insome situations, it can be desirable to prepare a low bulk densitymaterial, e.g., by densifying the material (e.g., densification can makeit easier and less costly to transport to another site) and thenreverting the material to a lower bulk density state (e.g., aftertransport). The material can be densified, for example from less thanabout 0.2 g/cc to more than about 0.9 g/cc (e.g., less than about 0.3 tomore than about 0.5 g/cc, less than about 0.3 to more than about 0.9g/cc, less than about 0.5 to more than about 0.9 g/cc, less than about0.3 to more than about 0.8 g/cc, less than about 0.2 to more than about0.5 g/cc). For example, the material can be densified by the methods andequipment disclosed in U.S. Pat. No. 7,932,065 to Medoff andInternational Publication No. WO 2008/073186 published Jun. 19, 2008(which was filed Oct. 26, 2007, was published in English, and whichdesignated the United States), the full disclosures of which areincorporated herein by reference. Densified materials can be processedby any of the methods described herein, or any material processed by anyof the methods described herein can be subsequently densified.

In some embodiments, the material to be processed is in the form of afibrous material that includes fibers provided by shearing a fibersource. For example, the shearing can be performed with a rotary knifecutter.

For example, a fiber source, e.g., that is recalcitrant or that has hadits recalcitrance level reduced, can be sheared, e.g., in a rotary knifecutter, to provide a first fibrous material. The first fibrous materialis passed through a first screen, e.g., having an average opening sizeof 1.59 mm or less ( 1/16 inch, 0.0625 inch), provide a second fibrousmaterial. If desired, the fiber source can be cut prior to the shearing,e.g., with a shredder. For example, when a paper is used as the fibersource, the paper can be first cut into strips that are, e.g., ¼- to½-inch wide, using a shredder, e.g., a counter-rotating screw shredder,such as those manufactured by Munson (Utica, N.Y.). As an alternative toshredding, the paper can be reduced in size by cutting to a desired sizeusing a guillotine cutter. For example, the guillotine cutter can beused to cut the paper into sheets that are, e.g., 10 inches wide by 12inches long.

In some embodiments, the shearing of the fiber source and the passing ofthe resulting first fibrous material through a first screen areperformed concurrently. The shearing and the passing can also beperformed in a batch-type process.

For example, a rotary knife cutter can be used to concurrently shear thefiber source and screen the first fibrous material. A rotary knifecutter includes a hopper that can be loaded with a shredded fiber sourceprepared by shredding a fiber source. The shredded fiber source.

In some implementations, the feedstock is physically treated prior tosaccharification and/or fermentation. Physical treatment processes caninclude one or more of any of those described herein, such as mechanicaltreatment, chemical treatment, irradiation, sonication, oxidation,pyrolysis or steam explosion. Treatment methods can be used incombinations of two, three, four, or even all of these technologies (inany order). When more than one treatment method is used, the methods canbe applied at the same time or at different times. Other processes thatchange a molecular structure of a biomass feedstock may also be used,alone or in combination with the processes disclosed herein.

Mechanical treatments that may be used, and the characteristics of themechanically treated biomass materials, are described in further detailin U.S. Pat. App. Pub. 2012/0100577 A1, filed Oct. 18, 2011, publishedApr. 26, 2013, the full disclosure of which is hereby incorporatedherein by reference.

Treatment of Biomass Material—Particle Bombardment

One or more treatments with energetic particle bombardment can be usedto process raw feedstock from a wide variety of different sources toextract useful substances from the feedstock, and to provide partiallydegraded organic material which functions as input to further processingsteps and/or sequences. Particle bombardment can reduce the molecularweight and/or crystallinity of feedstock. In some embodiments, energydeposited in a material that releases an electron from its atomicorbital can be used to treat the materials. The bombardment may beprovided by heavy charged particles (such as alpha particles orprotons), electrons (produced, for example, in beta decay or electronbeam accelerators), or electromagnetic radiation (for example, gammarays, x rays, or ultraviolet rays). Alternatively, radiation produced byradioactive substances can be used to treat the feedstock. Anycombination, in any order, or concurrently of these treatments may beutilized. In another approach, electromagnetic radiation (e.g., producedusing electron beam emitters) can be used to treat the feedstock.

Each form of energy ionizes the biomass via particular interactions.Heavy charged particles primarily ionize matter via Coulomb scattering;furthermore, these interactions produce energetic electrons that mayfurther ionize matter. Alpha particles are identical to the nucleus of ahelium atom and are produced by the alpha decay of various radioactivenuclei, such as isotopes of bismuth, polonium, astatine, radon,francium, radium, several actinides, such as actinium, thorium, uranium,neptunium, curium, californium, americium, and plutonium.

When particles are utilized, they can be neutral (uncharged), positivelycharged or negatively charged. When charged, the charged particles canbear a single positive or negative charge, or multiple charges, e.g.,one, two, three or even four or more charges. In instances in whichchain scission is desired, positively charged particles may bedesirable, in part, due to their acidic nature. When particles areutilized, the particles can have the mass of a resting electron, orgreater, e.g., 500, 1000, 1500, or 2000 or more times the mass of aresting electron. For example, the particles can have a mass of fromabout 1 atomic unit to about 150 atomic units, e.g., from about 1 atomicunit to about 50 atomic units, or from about 1 to about 25, e.g., 1, 2,3, 4, 5, 10, 12 or 15 atomic units. Accelerators used to accelerate theparticles can be electrostatic DC, electrodynamic DC, RF linear,magnetic induction linear or continuous wave. For example, cyclotrontype accelerators are available from IBA (Ion Beam Accelerators,Louvain-la-Neuve, Belgium), such as the Rhodotron™ system, while DC typeaccelerators are available from RDI, now IBA Industrial, such as theDynamitron™. Ions and ion accelerators are discussed in IntroductoryNuclear Physics, Kenneth S. Krane, John Wiley & Sons, Inc. (1988), KrstoPrelec, FIZIKA B 6 (1997) 4, 177-206; Chu, William T., “Overview ofLight-Ion Beam Therapy”, Columbus-Ohio, ICRU-IAEA Meeting, 18-20 Mar.2006; Iwata, Y. et al., “Alternating-Phase-Focused IH-DTL for Heavy-IonMedical Accelerators”, Proceedings of EPAC 2006, Edinburgh, Scotland;and Leitner, C. M. et al., “Status of the Superconducting ECR Ion SourceVenus”, Proceedings of EPAC 2000, Vienna, Austria.

The doses applied depend on the desired effect and the particularfeedstock. For example, high doses can break chemical bonds withinfeedstock components and low doses can increase chemical bonding (e.g.,cross-linking) within feedstock components.

In some instances when chain scission is desirable and/or polymer chainfunctionalization is desirable, particles heavier than electrons, suchas protons, helium nuclei, argon ions, silicon ions, neon ions, carbonions, phosphorus ions, oxygen ions or nitrogen ions can be utilized.When ring-opening chain scission is desired, positively chargedparticles can be utilized for their Lewis acid properties for enhancedring-opening chain scission. For example, when oxygen-containingfunctional groups are desired, treatment in the presence of oxygen oreven treatment with oxygen ions can be performed. For example, whennitrogen-containing functional groups are desirable, treatment in thepresence of nitrogen or even treatment with nitrogen ions can beperformed.

Other Forms of Energy

Electrons interact via Coulomb scattering and bremsstrahlung radiationproduced by changes in the velocity of electrons. Electrons may beproduced by radioactive nuclei that undergo beta decay, such as isotopesof iodine, cesium, technetium, and iridium. Alternatively, an electrongun can be used as an electron source via thermionic emission.

Electromagnetic radiation interacts via three processes: photoelectricabsorption, Compton scattering, and pair production. The dominatinginteraction is determined by the energy of the incident radiation andthe atomic number of the material. The summation of interactionscontributing to the absorbed radiation in cellulosic material can beexpressed by the mass absorption coefficient.

Electromagnetic radiation is subclassified as gamma rays, x rays,ultraviolet rays, infrared rays, microwaves, or radiowaves, depending onthe wavelength.

For example, gamma radiation can be employed to treat the materials.Gamma radiation has the advantage of a significant penetration depthinto a variety of material in the sample. Sources of gamma rays includeradioactive nuclei, such as isotopes of cobalt, calcium, technetium,chromium, gallium, indium, iodine, iron, krypton, samarium, selenium,sodium, thalium, and xenon.

Sources of x rays include electron beam collision with metal targets,such as tungsten or molybdenum or alloys, or compact light sources, suchas those produced commercially by Lyncean.

Sources for ultraviolet radiation include deuterium or cadmium lamps.

Sources for infrared radiation include sapphire, zinc, or selenidewindow ceramic lamps.

Sources for microwaves include klystrons, Slevin type RF sources, oratom beam sources that employ hydrogen, oxygen, or nitrogen gases.

Various other devices may be used in the methods disclosed herein,including field ionization sources, electrostatic ion separators, fieldionization generators, thermionic emission sources, microwave dischargeion sources, recirculating or static accelerators, dynamic linearaccelerators, van de Graaff accelerators, and folded tandemaccelerators. Such devices are disclosed, for example, in U.S. Pat. No.7,931,784 B2, the complete disclosure of which is incorporated herein byreference.

Treatment of Biomass Material—Electron Bombardment

The feedstock may be treated with electron bombardment to modify itsstructure and thereby reduce its recalcitrance. Such treatment may, forexample, reduce the average molecular weight of the feedstock, changethe crystalline structure of the feedstock, and/or increase the surfacearea and/or porosity of the feedstock.

Electron bombardment via an electron beam is generally preferred,because it provides very high throughput and because the use of arelatively low voltage/high power electron beam device eliminates theneed for expensive concrete vault shielding, as such devices are“self-shielded” and provide a safe, efficient process. While the“self-shielded” devices do include shielding (e.g., metal plateshielding), they do not require the construction of a concrete vault,greatly reducing capital expenditure and often allowing an existingmanufacturing facility to be used without expensive modification.Electron beam accelerators are available, for example, from IBA (IonBeam Applications, Louvain-la-Neuve, Belgium), Titan Corporation (SanDiego, Calif., USA), and NHV Corporation (Nippon High Voltage, Japan).

Electron bombardment may be performed using an electron beam device thathas a nominal energy of less than 10 MeV, e.g., less than 7 MeV, lessthan 5 MeV, or less than 2 MeV, e.g., from about 0.5 to 1.5 MeV, fromabout 0.8 to 1.8 MeV, from about 0.7 to 1 MeV, or from about 1 to 3 MeV.In some implementations the nominal energy is about 500 to 800 keV.

The electron beam may have a relatively high total beam power (thecombined beam power of all accelerating heads, or, if multipleaccelerators are used, of all accelerators and all heads), e.g., atleast 25 kW, e.g., at least 30, 40, 50, 60, 65, 70, 80, 100, 125, or 150kW. In some cases, the power is even as high as 500 kW, 750 kW, or even1000 kW or more. In some cases the electron beam has a beam power of1200 kW or more.

This high total beam power is usually achieved by utilizing multipleaccelerating heads. For example, the electron beam device may includetwo, four, or more accelerating heads. The use of multiple heads, eachof which has a relatively low beam power, prevents excessive temperaturerise in the material, thereby preventing burning of the material, andalso increases the uniformity of the dose through the thickness of thelayer of material.

In some implementations, it is desirable to cool the material duringelectron bombardment. For example, the material can be cooled while itis being conveyed, for example by a screw extruder or other conveyingequipment.

To reduce the energy required by the recalcitrance-reducing process, itis desirable to treat the material as quickly as possible. In general,it is preferred that treatment be performed at a dose rate of greaterthan about 0.25 Mrad per second, e.g., greater than about 0.5, 0.75, 1,1.5, 2, 5, 7, 10, 12, 15, or even greater than about 20 Mrad per second,e.g., about 0.25 to 2 Mrad per second. Higher dose rates generallyrequire higher line speeds, to avoid thermal decomposition of thematerial. In one implementation, the accelerator is set for 3 MeV, 50mAmp beam current, and the line speed is 24 feet/minute, for a samplethickness of about 20 mm (e.g., comminuted corn cob material with a bulkdensity of 0.5 g/cm³).

In some embodiments, electron bombardment is performed until thematerial receives a total dose of at least 0.5 Mrad, e.g., at least 5,10, 20, 30 or at least 40 Mrad. In some embodiments, the treatment isperformed until the material receives a dose of from about 0.5 Mrad toabout 150 Mrad, about 1 Mrad to about 100 Mrad, about 2 Mrad to about 75Mrad, 10 Mrad to about 50 Mrad, e.g., about 5 Mrad to about 50 Mrad,from about 20 Mrad to about 40 Mrad, about 10 Mrad to about 35 Mrad, orfrom about 25 Mrad to about 30 Mrad. In some implementations, a totaldose of 25 to 35 Mrad is preferred, applied ideally over a couple ofseconds, e.g., at 5 Mrad/pass with each pass being applied for about onesecond. Applying a dose of greater than 7 to 8 Mrad/pass can in somecases cause thermal degradation of the feedstock material.

Using multiple heads as discussed above, the material can be treated inmultiple passes, for example, two passes at 10 to 20 Mrad/pass, e.g., 12to 18 Mrad/pass, separated by a few seconds of cool-down, or threepasses of 7 to 12 Mrad/pass, e.g., 9 to 11 Mrad/pass. As discussedabove, treating the material with several relatively low doses, ratherthan one high dose, tends to prevent overheating of the material andalso increases dose uniformity through the thickness of the material. Insome implementations, the material is stirred or otherwise mixed duringor after each pass and then smoothed into a uniform layer again beforethe next pass, to further enhance treatment uniformity.

In some embodiments, electrons are accelerated to, for example, a speedof greater than 75 percent of the speed of light, e.g., greater than 85,90, 95, or 99 percent of the speed of light.

In some embodiments, any processing described herein occurs onlignocellulosic material that remains dry as acquired or that has beendried, e.g., using heat and/or reduced pressure. For example, in someembodiments, the cellulosic and/or lignocellulosic material has lessthan about five percent by weight retained water, measured at 25° C. andat fifty percent relative humidity.

Electron bombardment can be applied while the cellulosic and/orlignocellulosic material is exposed to air, oxygen-enriched air, or evenoxygen itself, or blanketed by an inert gas such as nitrogen, argon, orhelium. When maximum oxidation is desired, an oxidizing environment isutilized, such as air or oxygen and the distance from the beam source isoptimized to maximize reactive gas formation, e.g., ozone and/or oxidesof nitrogen.

In some embodiments, two or more electron sources are used, such as twoor more ionizing sources. For example, samples can be treated, in anyorder, with a beam of electrons, followed by gamma radiation and UVlight having wavelengths from about 100 nm to about 280 nm. In someembodiments, samples are treated with three ionizing radiation sources,such as a beam of electrons, gamma radiation, and energetic UV light.The biomass is conveyed through the treatment zone where it can bebombarded with electrons. It is generally preferred that the bed ofbiomass material has a relatively uniform thickness, as previouslydescribed, while being treated.

It may be advantageous to repeat the treatment to more thoroughly reducethe recalcitrance of the biomass and/or further modify the biomass. Inparticular the process parameters can be adjusted after a first (e.g.,second, third, fourth or more) pass depending on the recalcitrance ofthe material. In some embodiments, a conveyor can be used which includesa circular system where the biomass is conveyed multiple times throughthe various processes described above. In some other embodimentsmultiple treatment devices (e.g., electron beam generators) are used totreat the biomass multiple (e.g., 2, 3, 4 or more) times. In yet otherembodiments, a single electron beam generator may be the source ofmultiple beams (e.g., 2, 3, 4 or more beams) that can be used fortreatment of the biomass.

The effectiveness in changing the molecular/supermolecular structureand/or reducing the recalcitrance of the biomass depends on the electronenergy used and the dose applied, while exposure time depends on thepower and dose.

In some embodiments, the treatment (with any electron source or acombination of sources) is performed until the material receives a doseof at least about 0.05 Mrad, e.g., at least about 0.1, 0.25, 0.5, 0.75,1.0, 2.5, 5.0, 7.5, 10.0, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90, 100,125, 150, 175, or 200 Mrad. In some embodiments, the treatment isperformed until the material receives a dose of between 0.1-100 Mrad,1-200, 5-200, 10-200, 5-150, 5-100, 5-50, 5-40, 10-50, 10-75, 15-50,20-35 Mrad.

In some embodiments, the treatment is performed at a dose rate ofbetween 5.0 and 1500.0 kilorads/hour, e.g., between 10.0 and 750.0kilorads/hour or between 50.0 and 350.0 kilorads/hours. In otherembodiments the treatment is performed at a dose rate of between 10 and10000 kilorads/hr, between 100 and 1000 kilorad/hr, or between 500 and1000 kilorads/hr.

Electron Sources

Electrons interact via Coulomb scattering and bremsstrahlung radiationproduced by changes in the velocity of electrons. Electrons may beproduced by radioactive nuclei that undergo beta decay, such as isotopesof iodine, cesium, technetium, and iridium. Alternatively, an electrongun can be used as an electron source via thermionic emission andaccelerated through an accelerating potential. An electron gun generateselectrons, accelerates them through a large potential (e.g., greaterthan about 500 thousand, greater than about 1 million, greater thanabout 2 million, greater than about 5 million, greater than about 6million, greater than about 7 million, greater than about 8 million,greater than about 9 million, or even greater than 10 million volts) andthen scans them magnetically in the x-y plane, where the electrons areinitially accelerated in the z direction down the tube and extractedthrough a foil window. Scanning the electron beam is useful forincreasing the irradiation surface when irradiating materials, e.g., abiomass, that is conveyed through the scanned beam. Scanning theelectron beam also distributes the thermal load homogenously on thewindow and helps reduce the foil window rupture due to local heating bythe electron beam. Window foil rupture is a cause of significantdown-time due to subsequent necessary repairs and re-starting theelectron gun.

Various other irradiating devices may be used in the methods disclosedherein, including field ionization sources, electrostatic ionseparators, field ionization generators, thermionic emission sources,microwave discharge ion sources, recirculating or static accelerators,dynamic linear accelerators, van de Graaff accelerators, and foldedtandem accelerators. Such devices are disclosed, for example, in U.S.Pat. No. 7,931,784 to Medoff, the complete disclosure of which isincorporated herein by reference.

A beam of electrons can be used as the radiation source. A beam ofelectrons has the advantages of high dose rates (e.g., 1, 5, or even 10Mrad per second), high throughput, less containment, and lessconfinement equipment. Electron beams can also have high electricalefficiency (e.g., 80%), allowing for lower energy usage relative toother radiation methods, which can translate into a lower cost ofoperation and lower greenhouse gas emissions corresponding to thesmaller amount of energy used. Electron beams can be generated, e.g., byelectrostatic generators, cascade generators, transformer generators,low energy accelerators with a scanning system, low energy acceleratorswith a linear cathode, linear accelerators, and pulsed accelerators.

Electrons can also be more efficient at causing changes in the molecularstructure of biomass materials, for example, by the mechanism of chainscission. In addition, electrons having energies of 0.5-10 MeV canpenetrate low density materials, such as the biomass materials describedherein, e.g., materials having a bulk density of less than 0.5 g/cm³,and a depth of 0.3-10 cm. Electrons as an ionizing radiation source canbe useful, e.g., for relatively thin piles, layers or beds of materials,e.g., less than about 0.5 inch, e.g., less than about 0.4 inch, 0.3inch, 0.25 inch, or less than about 0.1 inch. In some embodiments, theenergy of each electron of the electron beam is from about 0.3 MeV toabout 2.0 MeV (million electron volts), e.g., from about 0.5 MeV toabout 1.5 MeV, or from about 0.7 MeV to about 1.25 MeV. Methods ofirradiating materials are discussed in U.S. Pat. App. Pub. 2012/0100577A1, filed Oct. 18, 2011, published Apr. 26, 2012, the entire disclosureof which is herein incorporated by reference.

Electron beam irradiation devices may be procured commercially from IonBeam Applications (Louvain-la-Neuve, Belgium), the Titan Corporation(San Diego, Calif., USA), and NHV Corporation (Nippon High Voltage,Japan). Typical electron energies can be 0.5 MeV, 1 MeV, 2 MeV, 4.5 MeV,7.5 MeV, or 10 MeV. Typical electron beam irradiation device power canbe 1 KW, 5 KW, 10 KW, 20 KW, 50 KW, 60 KW, 70 KW, 80 KW, 90 KW, 100 KW,125 KW, 150 KW, 175 KW, 200 KW, 250 KW, 300 KW, 350 KW, 400 KW, 450 KW,500 KW, 600 KW, 700 KW, 800 KW, 900 KW or even 1000 KW.

Tradeoffs in considering electron beam irradiation device powerspecifications include cost to operate, capital costs, depreciation, anddevice footprint. Tradeoffs in considering exposure dose levels ofelectron beam irradiation would be energy costs and environment, safety,and health (ESH) concerns. Typically, generators are housed in a vault,e.g., of lead or concrete, especially for production from X-rays thatare generated in the process. Tradeoffs in considering electron energiesinclude energy costs.

The electron beam irradiation device can produce either a fixed beam ora scanning beam. A scanning beam may be advantageous with large scansweep length and high scan speeds, as this would effectively replace alarge, fixed beam width. Further, available sweep widths of 0.5 m, 1 m,2 m or more are available. The scanning beam is preferred in mostembodiments describe herein because of the larger scan width and reducedpossibility of local heating and failure of the windows.

Treatment of Biomass Material—Sonication, Pyrolysis, Oxidation, SteamExplosion

If desired, one or more sonication, pyrolysis, oxidative, or steamexplosion processes can be used in addition to or instead of othertreatments to further reduce the recalcitrance of the biomass material.These processes can be applied before, during and/or after anothertreatment or treatments. These processes are described in detail in U.S.Pat. No. 7,932,065 to Medoff, the full disclosure of which isincorporated herein by reference.

Use of Treated Biomass Material

Using the methods described herein, a starting biomass material (e.g.,plant biomass, animal biomass, paper, and municipal waste biomass) canbe used as feedstock to produce useful intermediates and products suchas organic acids, salts of organic acids, anhydrides, esters of organicacids and fuels, e.g., fuels for internal combustion engines orfeedstocks for fuel cells. Systems and processes are described hereinthat can use as feedstock cellulosic and/or lignocellulosic materialsthat are readily available, but often can be difficult to process, e.g.,municipal waste streams and waste paper streams, such as streams thatinclude newspaper, kraft paper, corrugated paper or mixtures of these.

In order to convert the feedstock to a form that can be readilyprocessed, the glucan- or xylan-containing cellulose in the feedstockcan be hydrolyzed to low molecular weight carbohydrates, such as sugars,by a saccharifying agent, e.g., an enzyme or acid, a process referred toas saccharification. The low molecular weight carbohydrates can then beused, for example, in an existing manufacturing plant, such as a singlecell protein plant, an enzyme manufacturing plant, or a fuel plant,e.g., an ethanol manufacturing facility.

The feedstock can be hydrolyzed using an enzyme, e.g., by combining thematerials and the enzyme in a solvent, e.g., in an aqueous solution.

Alternatively, the enzymes can be supplied by organisms that break downbiomass, such as the cellulose and/or the lignin portions of thebiomass, contain or manufacture various cellulolytic enzymes(cellulases), ligninases or various small molecule biomass-degradingmetabolites. These enzymes may be a complex of enzymes that actsynergistically to degrade crystalline cellulose or the lignin portionsof biomass. Examples of cellulolytic enzymes include: endoglucanases,cellobiohydrolases, and cellobiases (beta-glucosidases).

During saccharification a cellulosic substrate can be initiallyhydrolyzed by endoglucanases at random locations producing oligomericintermediates. These intermediates are then substrates for exo-splittingglucanases such as cellobiohydrolase to produce cellobiose from the endsof the cellulose polymer. Cellobiose is a water-soluble 1,4-linked dimerof glucose. Finally, cellobiase cleaves cellobiose to yield glucose. Theefficiency (e.g., time to hydrolyze and/or completeness of hydrolysis)of this process depends on the recalcitrance of the cellulosic material.

Intermediates and Products

The processes described herein are preferably used to produce butanol,e.g., isobutanol or n-butanol, and derivatives. However, the processesmay be used to produce other products, co-products and intermediates,for example, the products described in U.S. Pat. App. Pub. 2012/0100577A1, filed Oct. 18, 2011 and published Apr. 26, 2012, the full disclosureof which is incorporated herein by reference.

Using the processes described herein, the biomass material can beconverted to one or more products, such as energy, fuels, foods andmaterials. Specific examples of products include, but are not limitedto, hydrogen, sugars (e.g., glucose, xylose, arabinose, mannose,galactose, fructose, disaccharides, oligosaccharides andpolysaccharides), alcohols (e.g., monohydric alcohols or dihydricalcohols, such as ethanol, n-propanol, isobutanol, sec-butanol,tert-butanol or n-butanol), hydrated or hydrous alcohols (e.g.,containing greater than 10%, 20%, 30% or even greater than 40% water),biodiesel, organic acids, hydrocarbons (e.g., methane, ethane, propane,isobutene, pentane, n-hexane, biodiesel, bio-gasoline and mixturesthereof), co-products (e.g., proteins, such as cellulolytic proteins(enzymes) or single cell proteins), and mixtures of any of these in anycombination or relative concentration, and optionally in combinationwith any additives (e.g., fuel additives). Other examples includecarboxylic acids, salts of a carboxylic acid, a mixture of carboxylicacids and salts of carboxylic acids and esters of carboxylic acids(e.g., methyl, ethyl and n-propyl esters), ketones (e.g., acetone),aldehydes (e.g., acetaldehyde), alpha and beta unsaturated acids (e.g.,acrylic acid) and olefins (e.g., ethylene). Other alcohols and alcoholderivatives include propanol, propylene glycol, 1,4-butanediol,1,3-propanediol, sugar alcohols and polyols (e.g., glycol, glycerol,erythritol, threitol, arabitol, xylitol, ribitol, mannitol, sorbitol,galactitol, iditol, inositol, volemitol, isomalt, maltitol, lactitol,maltotriitol, maltotetraitol, and polyglycitol and other polyols), andmethyl or ethyl esters of any of these alcohols. Other products includemethyl acrylate, methylmethacrylate, lactic acid, citric acid, formicacid, acetic acid, propionic acid, butyric acid, succinic acid, valericacid, caproic acid, 3-hydroxypropionic acid, palmitic acid, stearicacid, oxalic acid, malonic acid, glutaric acid, oleic acid, linoleicacid, glycolic acid, gamma-hydroxybutyric acid, and mixtures thereof,salts of any of these acids, mixtures of any of the acids and theirrespective salts.

Any combination of the above products with each other, and/or of theabove products with other products, which other products may be made bythe processes described herein or otherwise, may be packaged togetherand sold as products. The products may be combined, e.g., mixed, blendedor co-dissolved, or may simply be packaged or sold together.

Any of the products or combinations of products described herein may besanitized or sterilized prior to selling the products, e.g., afterpurification or isolation or even after packaging, to neutralize one ormore potentially undesirable contaminants that could be present in theproduct(s). Such sanitation can be done with electron bombardment, forexample, be at a dosage of less than about 20 Mrad, e.g., from about 0.1to 15 Mrad, from about 0.5 to 7 Mrad, or from about 1 to 3 Mrad.

The processes described herein can produce various by-product streamsuseful for generating steam and electricity to be used in other parts ofthe plant (co-generation) or sold on the open market. For example, steamgenerated from burning by-product streams can be used in a distillationprocess. As another example, electricity generated from burningby-product streams can be used to power electron beam generators used inpretreatment.

The by-products used to generate steam and electricity are derived froma number of sources throughout the process. For example, anaerobicdigestion of wastewater can produce a biogas high in methane and a smallamount of waste biomass (sludge). As another example,post-saccharification and/or post-distillate solids (e.g., unconvertedlignin, cellulose, and hemicellulose remaining from the pretreatment andprimary processes) can be used, e.g., burned, as a fuel.

Many of the products obtained, such as ethanol or n-butanol, can beutilized as a fuel for powering cars, trucks, tractors, ships or trains,e.g., as an internal combustion fuel or as a fuel cell feedstock. Manyof the products obtained can also be utilized to power aircraft, such asplanes, e.g., having jet engines or helicopters. In addition, theproducts described herein can be utilized for electrical powergeneration, e.g., in a conventional steam generating plant or in a fuelcell plant.

Other intermediates and products, including food and pharmaceuticalproducts, are described in U.S. Pat. App. Pub. 2010/0124583 A1,published May 20, 2010, to Medoff, the full disclosure of which ishereby incorporated by reference herein.

Post-Processing

The process for purification of products may include using ion-exchangeresins, activated charcoal, filtration, distillation, centrifugation,chromatography, precipitation, crystallization, evaporation, adsorptionand combinations thereof. In some cases, the fermentation product isalso sterilized, e.g., by heat or irradiation.

Saccharification

To obtain a fructose solution from the reduced-relacitrance feedstock,the treated biomass materials can be saccharified, generally bycombining the material and a cellulase enzyme in a fluid medium, e.g.,an aqueous solution. In some cases, the material is boiled, steeped, orcooked in hot water prior to saccharification, as described in U.S. Pat.App. Pub. 2012/0100577 A1 by Medoff and Masterman, published on Apr. 26,2012, the entire contents of which are incorporated herein.

The saccharification process can be partially or completely performed ina tank (e.g., a tank having a volume of at least 4000, 40,000, or500,000 L) in a manufacturing plant, and/or can be partially orcompletely performed in transit, e.g., in a rail car, tanker truck, orin a supertanker or the hold of a ship. The time required for completesaccharification will depend on the process conditions and the biomassmaterial and enzyme used. If saccharification is performed in amanufacturing plant under controlled conditions, the cellulose may besubstantially entirely converted to sugar, e.g., glucose in about 12-96hours. If saccharification is performed partially or completely intransit, saccharification may take longer.

It is generally preferred that the tank contents be mixed duringsaccharification, e.g., using jet mixing as described in InternationalApp. No. PCT/US2010/035331, filed May 18, 2010, which was published inEnglish as WO 2010/135380 Nov. 25, 2010 and designated the UnitedStates, the full disclosure of which is incorporated by referenceherein.

The addition of surfactants can enhance the rate of saccharification.Examples of surfactants include non-ionic surfactants, such as a Tween®20 or Tween® 80 polyethylene glycol surfactants, ionic surfactants, oramphoteric surfactants.

It is generally preferred that the concentration of the sugar solutionresulting from saccharification be relatively high, e.g., greater than40%, or greater than 50, 60, 70, 80, 90 or even greater than 95% byweight. Water may be removed, e.g., by evaporation, to increase theconcentration of the sugar solution. This reduces the volume to beshipped, and also inhibits microbial growth in the solution.

Alternatively, sugar solutions of lower concentrations may be used, inwhich case it may be desirable to add an antimicrobial additive, e.g., abroad spectrum antibiotic, in a low concentration, e.g., 50 to 150 ppm.Other suitable antibiotics include amphotericin B, ampicillin,chloramphenicol, ciprofloxacin, gentamicin, hygromycin B, kanamycin,neomycin, penicillin, puromycin, streptomycin. Antibiotics will inhibitgrowth of microorganisms during transport and storage, and can be usedat appropriate concentrations, e.g., between 15 and 1000 ppm by weight,e.g., between 25 and 500 ppm, or between 50 and 150 ppm. If desired, anantibiotic can be included even if the sugar concentration is relativelyhigh. Alternatively, other additives with anti-microbial of preservativeproperties may be used. Preferably the antimicrobial additive(s) arefood-grade.

A relatively high concentration solution can be obtained by limiting theamount of water added to the biomass material with the enzyme. Theconcentration can be controlled, e.g., by controlling how muchsaccharification takes place. For example, concentration can beincreased by adding more biomass material to the solution. In order tokeep the sugar that is being produced in the solution, a surfactant canbe added, e.g., one of those discussed above. Solubility can also beincreased by increasing the temperature of the solution. For example,the solution can be maintained at a temperature of 40-50° C., 60-80° C.,or even higher.

By adding glucose isomerase to the contents of the tank, a highconcentration of fructose can be obtained without saccharification beinginhibited by the sugars in the tank. Glucose isomerase can be added inany amount. For example, the concentration may be below about 500 U/g ofcellulose (lower than or equal to 100 U/g cellulose, lower than or equalto 50 U/g cellulose, lower than or equal to 10 U/g cellulose, lower thanor equal to 5 U/g cellulose). The concentration is at least about 0.1U/g cellulose (at least about 0.5 U/g cellulose, at least about 1 U/gcellulose, at least about 2 U/g cellulose, at least about 3 U/gcellulose).

The addition of glucose isomerase increases the amount of sugarsproduced by at least 5% (at least 10%, at least to 15%, at least 20%).

The concentration of sugars in the solution can also be enhanced bylimiting the amount of water added to the feedstock with the enzyme,and/or the concentration can be increased by adding more feedstock tothe solution during saccharification. In order to keep the sugar that isbeing produced in the solution, a surfactant can be added, e.g., one ofthose discussed above. Solubility can also be increased by increasingthe temperature of the solution. For example, the solution can bemaintained at a temperature of 40-50° C., 60-80° C., or even higher.

Saccharifying Agents

Suitable cellulolytic enzymes include cellulases. Cellulases can beobtained, for example, from species in the genera Bacillus, Coprinus,Myceliophthora, Cephalosporium, Scytalidium, Penicillium, Aspergillus,Pseudomonas, Humicola, Fusarium, Thielavia, Acremonium, Chrysosporiumand Trichoderma, especially those produced by a strain selected from thespecies Aspergillus (see, e.g., EP Pub. No. 0 458 162), Humicolainsolens (reclassified as Scytalidium thermophilum, see, e.g., U.S. Pat.No. 4,435,307), Coprinus cinereus, Fusarium oxysporum, Myceliophthorathermophila, Meripilus giganteus, Thielavia terrestris, Acremonium sp.(including, but not limited to, A. persicinum, A. acremonium, A.brachypenium, A. dichromosporum, A. obclavatum, A. pinkertoniae, A.roseogriseum, A. incoloratum, and A. furatum). Preferred strains includeHumicola insolens DSM 1800, Fusarium oxysporum DSM 2672, Myceliophthorathermophila CBS 117.65, Cephalosporium sp. RYM-202, Acremonium sp. CBS478.94, Acremonium sp. CBS 265.95, Acremonium persicinum CBS 169.65,Acremonium acremonium AHU 9519, Cephalosporium sp. CBS 535.71,Acremonium brachypenium CBS 866.73, Acremonium dichromosporum CBS683.73, Acremonium obclavatum CBS 311.74, Acremonium pinkertoniae CBS157.70, Acremonium roseogriseum CBS 134.56, Acremonium incoloratum CBS146.62, and Acremonium furatum CBS 299.70H. Cellulolytic enzymes mayalso be obtained from Chrysosporium, preferably a strain ofChrysosporium lucknowense. Additional strains that can be used include,but are not limited to, Trichoderma (particularly T. viride, T. reesei,and T. koningii), alkalophilic Bacillus (see, for example, U.S. Pat. No.3,844,890 and EP Pub. No. 0 458 162), and Streptomyces (see, e.g., EPPub. No. 0 458 162).

Many microorganisms that can be used to saccharify biomass material andproduce sugars can also be used to ferment and convert those sugars touseful products.

Sugars

In the processes described herein, for example after saccharification,sugars (e.g., glucose and xylose) can be isolated. For example sugarscan be isolated by precipitation, crystallization, chromatography (e.g.,simulated moving bed chromatography, high pressure chromatography),centrifugation, extraction, any other isolation method known in the art,and combinations thereof.

Hydrogenation and Other Chemical Transformations

The processes described herein can include hydrogenation. For exampleglucose and xylose can be hydrogenated to sorbitol and xylitolrespectively. Hydrogenation can be accomplished by use of a catalyst(e.g., Pt/gamma-Al₂O₃, Ru/C, Raney Nickel, or other catalysts know inthe art) in combination with H₂ under high pressure (e.g., 10 to 12000psi). Other types of chemical transformation of the products from theprocesses described herein can be used, for example, production oforganic sugar derived products such (e.g., furfural and furfural-derivedproducts). Chemical transformations of sugar derived products aredescribed in U.S. application Ser. No. 13/934,704 filed Jul. 3, 2013,the disclosure of which is incorporated herein by reference in itsentirety.

Fermentation

Preferably, Clostridium spp. are used to convert sugars (e.g., fructose)to butanol. The optimum pH for fermentations is about pH 4 to 7. Forexample, the optimum pH for yeast is from about pH 4 to 5, while theoptimum pH for Zymomonas is from about pH 5 to 6. Typical fermentationtimes are about 24 to 168 hours (e.g., 24 to 96 hrs) with temperaturesin the range of 20° C. to 40° C. (e.g., 26° C. to 40° C.), howeverthermophilic microorganisms prefer higher temperatures.

In some embodiments, e.g., when anaerobic organisms are used, at least aportion of the fermentation is conducted in the absence of oxygen, e.g.,under a blanket of an inert gas such as N₂, Ar, He, CO₂ or mixturesthereof. Additionally, the mixture may have a constant purge of an inertgas flowing through the tank during part of or all of the fermentation.In some cases, anaerobic condition, can be achieved or maintained bycarbon dioxide production during the fermentation and no additionalinert gas is needed.

In some embodiments, all or a portion of the fermentation process can beinterrupted before the low molecular weight sugar is completelyconverted to a product (e.g., ethanol). The intermediate fermentationproducts include sugar and carbohydrates in high concentrations. Thesugars and carbohydrates can be isolated via any means known in the art.These intermediate fermentation products can be used in preparation offood for human or animal consumption. Additionally or alternatively, theintermediate fermentation products can be ground to a fine particle sizein a stainless-steel laboratory mill to produce a flour-like substance.

Jet mixing may be used during fermentation, and in some casessaccharification and fermentation are performed in the same tank.

Nutrients for the microorganisms may be added during saccharificationand/or fermentation, for example the food-based nutrient packagesdescribed in U.S. Pat. App. Pub. 2012/0052536, filed Jul. 15, 2011, thecomplete disclosure of which is incorporated herein by reference.

“Fermentation” includes the methods and products that are disclosed inU.S. Prov. App. No. 61/579,559, filed Dec. 22, 2012, and U.S. Prov. App.No. 61/579,576, filed Dec. 22, 2012, the contents of both of which areincorporated by reference herein in their entirety.

Mobile fermenters can be utilized, as described in International App.No. PCT/US2007/074028 (which was filed Jul. 20, 2007, was published inEnglish as WO 2008/011598 and designated the United States), thecontents of which is incorporated herein in its entirety. Similarly, thesaccharification equipment can be mobile. Further, saccharificationand/or fermentation may be performed in part or entirely during transit.

Fermentation Agents

Although Clostridium is preferred, other microorganisms can be used. Forinstance, yeast and Zymomonas bacteria can be used for fermentation orconversion of sugar(s) to other alcohol(s). Other microorganisms arediscussed below. They can be naturally-occurring microorganisms and/orengineered microorganisms. For example, the microorganism can be abacterium (including, but not limited to, e.g., a cellulolyticbacterium), a fungus, (including, but not limited to, e.g., a yeast), aplant, a protist, e.g., a protozoa or a fungus-like protest (including,but not limited to, e.g., a slime mold), or an algae. When the organismsare compatible, mixtures of organisms can be utilized.

Suitable fermenting microorganisms have the ability to convertcarbohydrates, such as glucose, fructose, xylose, arabinose, mannose,galactose, oligosaccharides or polysaccharides into fermentationproducts. Fermenting microorganisms include strains of the genusSaccharomyces spp. (including, but not limited to, S. cerevisiae(baker's yeast), S. distaticus, S. uvarum), the genus Kluyveromyces,(including, but not limited to, K. marxianus, K. fragilis), the genusCandida (including, but not limited to, C. pseudotropicalis, and C.brassicae), Pichia stipitis (a relative of Candida shehatae), the genusClavispora (including, but not limited to, C. lusitaniae and C.opuntiae), the genus Pachysolen (including, but not limited to, P.tannophilus), the genus Bretannomyces (including, but not limited to,e.g., B. clausenii (Philippidis, G. P., 1996, Cellulose bioconversiontechnology, in Handbook on Bioethanol: Production and Utilization,Wyman, C. E., ed., Taylor & Francis, Washington, D.C., 179-212)). Othersuitable microorganisms include, for example, Zymomonas mobilis,Clostridium spp. (including, but not limited to, C. thermocellum(Philippidis, 1996, supra), C. saccharobutylacetonicum, C.saccharobutylicum, C. Puniceum, C. beijernckii, and C. acetobutylicum),Moniliella pollinis, Moniliella megachiliensis, Lactobacillus spp.Yarrowia lipolytica, Aureobasidium sp., Trichosporonoides sp.,Trigonopsis variabilis, Trichosporon sp., Moniliellaacetoabutans sp.,Typhula variabilis, Candida magnoliae, Ustilaginomycetes sp., Pseudozymatsukubaensis, yeast species of genera Zygosaccharomyces, Debaryomyces,Hansenula and Pichia, and fungi of the dematioid genus Torula.

For instance, Clostridium spp. can be used to produce ethanol, butanol,butyric acid, acetic acid, and acetone. Lactobacillus spp., can be usedto produce lactic acid.

Many such microbial strains are publicly available, either commerciallyor through depositories such as the ATCC (American Type CultureCollection, Manassas, Va., USA), the NRRL (Agricultural Research ServiceCulture Collection, Peoria, Ill., USA), or the DSMZ (Deutsche Sammlungvon Mikroorganismen and Zellkulturen GmbH, Braunschweig, Germany), toname a few.

Commercially available yeasts include, for example, Red Star®/LesaffreEthanol Red (available from Red Star/Lesaffre, USA), FALI® (availablefrom Fleischmann's Yeast, a division of Burns Philip Food Inc., USA),SUPERSTART® (available from Alltech, now Lalemand), GERT STRAND®(available from Gert Strand AB, Sweden) and FERMOL® (available from DSMSpecialties).

Many microorganisms that can be used to saccharify biomass material andproduce sugars can also be used to ferment and convert those sugars touseful products.

Distillation

After fermentation, the resulting fluids can be distilled using, forexample, a “beer column” to separate ethanol and other alcohols from themajority of water and residual solids. The vapor exiting the beer columncan be, e.g., 35% by weight ethanol and can be fed to a rectificationcolumn. A mixture of nearly azeotropic (92.5%) ethanol and water fromthe rectification column can be purified to pure (99.5%) ethanol usingvapor-phase molecular sieves. The beer column bottoms can be sent to thefirst effect of a three-effect evaporator. The rectification columnreflux condenser can provide heat for this first effect. After the firsteffect, solids can be separated using a centrifuge and dried in a rotarydryer. A portion (25%) of the centrifuge effluent can be recycled tofermentation and the rest sent to the second and third evaporatoreffects. Most of the evaporator condensate can be returned to theprocess as fairly clean condensate with a small portion split off towaste water treatment to prevent build-up of low-boiling compounds.

Other than in the examples herein, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentages,such as those for amounts of materials, elemental contents, times andtemperatures of reaction, ratios of amounts, and others, in thefollowing portion of the specification and attached claims may be readas if prefaced by the word “about” even though the term “about” may notexpressly appear with the value, amount, or range. Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties sought to be obtained by thepresent invention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains errornecessarily resulting from the standard deviation found in itsunderlying respective testing measurements. Furthermore, when numericalranges are set forth herein, these ranges are inclusive of the recitedrange end points (i.e., end points may be used). When percentages byweight are used herein, the numerical values reported are relative tothe total weight.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10. The terms “one,” “a,” or “an”as used herein are intended to include “at least one” or “one or more,”unless otherwise indicated.

EXAMPLES Example 1. Materials & Methods

Preparation of Seed Cultures:

Moniliella cells stored at −80° C. were used to inoculate propagationmedium (20 g/L malt extract, 1 g/L peptone, 20 g/L glucose), andincubated at 30° C. and agitation of 200 rpm for 72 hours. The culturewas then transferred to a bioreactor (either 3 L, 20 L, or 400 L) forerythritol production.

Main Culture:

The erythritol production medium consists of 10 g/L yeast extract, 1 g/Lphytic acid, 1 g/L potassium nitrate, 100 g/L calcium chloride, 10 mg/Lcupric sulfate, 50 mg/L zinc chloride and either 300 g/L glucose(reagent grade from Sigma) or purified saccharified corncob preparedin-house.

The corn cob was treated with 35 Mrad from an electron beam, andsaccharified with cellulase prepared in-house. The saccharified corn cobwas then purified by cation exchange (Diaion PK228, Mitsubishi ChemicalCorporation) and anion exchange (Diaion JA300, Mitsubishi ChemicalCorporation).

Example 2. Determination of Culture Conditions

The bioreactor culture consisted of 1.5 L in a 3 L vessel, 10 L in a 20L vessel, or 250 L in a 400 L vessel. Inoculum for each consisted of72-hour cultured seed culture, added at 5% of the volume in thebioreactor. Aeration was adjusted to 0.3 to 1 VVM, the agitation was300-1000 rpm, and the temperature was 35° C. Antifoam 204 was addedcontinuously at a rate of 1.5 ml/L/day.

Twelve different yeast extracts were tested for their effect onerythritol production. The results were: Granulated Fisher (105 g/Lerythritol production), Thermo Oxoid (30 g/L), Bacto Tech (94 g/L),Fluka (108 g/L), Thermo Remel (111 g/L), Teknova (108 g/L), Acros (93g/L), Boston (96 g/L), Sunrise (8 g/L), US Biochem (88 g/L), Sigma (76g/L), and BD (90-120 g/L). Granulated Fisherm Bacto Tech, Fluka, ThermoRemel, Teknova, Acros, Boston, US Biochem, and BD were carried over foradditional testing.

Twelve different antifoam agents were tested. These were: Antifoam A, B,C, O-30, SE-15, Y-30, Silicone Antifoam, Antifoam 204 (all from SigmaChemical Company, St, Louis, Mo., USA), Antifoam AF (from Fisher), KFO880, KFO 770, and Foam Blast 779 (from Emerald Performance Materials).

TABLE 1a Medium Components Tested for Erythritol Production Mediumcomponent Range Tested Working Range* Optimal Range Phytic acid (cultureperiod) with phytic acid 3-4 days to reach max. prod. with phytic acidPhytic acid (culture period) without phytic acid 10-12 days to reachmax. prod. Phytic acid (amount) 0.3-9 g/L 0.3-1.0 g/L 0.3-1.0 g/L Sodiumphosphate monobasic 2-12 g/L 2-12 g/L (3-4 days lower yield than(culture period) to reach max. prod. phytic acid Calcium chloride(amount) 10-300 mg/L 10-150 mg/L 100 mg/L Glucose (amount) 150-600 g/L200-400 g/L 300 g/L Cupric sulfate (amount) 2-250 mg/L 2-250 mg/L 10mg/L Yeast extract (amount) 5-20 g/L 9-13 g/L 10 g/L Yeast extract(brand) 12 different brands 9 different brands Fluka YE Zinc chloride(amount) 25-100 mg/L 25-100 mg/L 50 mg/L Antifoam agent (brand) 12different agents KFO 880; Antifoam 204 Antifoam 204 Nitrogen source 5different sources Urea; Sodium nitrate; Potassium nitrate Ammoniumnitrate; Ammonium sulfate; Potassium nitrate Potassium nitrate (amount)0.5-5 g/L 0.5-5 g/L 1 g/L *“Working Range” was determined as conditionsthat produced greater than 80 g/L erythritol from 300 g/L glucose.

TABLE 1b Culture Conditions Tested for Erythritol Production RangeWorking Optimum Condition Tested Tested Range* Range Agitation (speed in450-1000 rpm 600-1000 rpm 800 rpm 3 L bioreactor) Agitation (speed in300-650 rpm 400-650 rpm 650 rpm 20 L bioreactor) Aeration (VVM) 0.3-1VVM 0.3-1 VVM 0.6 VVM Culture 30-40° C. 30-37° C. 35° C. TemperatureTurbulence (dip with/without dip with dip tube with dip tube tube in 400L tube bioreactor) *“Working Range” was determined as conditions thatproduced greater than 80 g/L erythritol from 300 g/L glucose.

Example 3. Bioreactor Culture of Moniliella in a 3 L Bioreactor

Moniliella pollinis (strain CBS 461.67; Centraalbureau voorSchimmelcultures, Utrecht, The Netherlands) was cultured in productionmedium in the 3 L bioreactor (1.5 L culture volume) with various mediumcomponents conditions (Table 1a). Phytic acid shortened culture periodto 3 to 4 days, while it took 10 to 12 days for erythritol productionwithout phytic acid (Table 1a). Each component (phytic acid, yeastextract, sodium phosphate monobasic, calcium chloride, glucose, cupricsulfate, zinc chloride, potassium nitrate) was tested for obtainingoptimal concentration (Table 1a). Physical conditions includingagitation, aeration, temperature were also tested (Table 1b). Typicalerythritol production was 80 to 120 g/L of erythritol from 300 g/L ofglucose.

The table below shows erythritol production in a 3 L bioreactor cultureof Moniliella strain CBS 461.67 with optimal concentrations of mediacomponents (300 g/L glucose, 10 g/L yeast extract, 1 g/L phytic acid, 1g/L potassium nitrate).

TABLE 2 Production of Erythritol and Other Products From 300 g/L GlucoseDay Glycerol Erythritol Ribitol Ethanol 0 0 0 0 0 1 7.13 3.66 0 5.39 233.50 35.69 3.51 9.68 3 33.77 92.13 4.79 2.86 4 16.89 88.51 4.92 0.45

Example 4. Bioreactor Culture of Moniliella in a 20 L Bioreactor

Agitation speed was found to greatly affect erythritol production.Erythritol was produced in a 10 L culture volume in a 20 L bioreactor atthree different speeds (300 rpm, 400 rpm, 650 rpm), at 1 VVM and 35° C.,in medium composed of yeast extract (10 g/L), KNO₃ (1 g/L), phytic acid(1 g/L), CuSO₄ (2 mg/L). The 400 rpm and 650 rpm cultures also includedthree impellers. The 650 rpm culture was aerated at 0.6 VVM, rather than1 VVM.

The bioreactor culture with 300 rpm of agitation speed resulted in muchlower erythritol production than the same culture at 650 rpm. Ethanolproduction, on the other hand, was decreased by increasing agitationspeed.

TABLE 3 Effect of Agitation Speed on Erythritol Production. Day GlycerolErythritol Ribitol Ethanol Glucose 300 rpm 0 4.09 3.35 0 2.63 >50 110.80 5.95 3.06 15.15 >50 2 18.48 19.39 0 24.44 >50 3 24.24 48.09 032.37 70.74 4 25.27 59.51 0 25.15 0 5 23.36 64.09 3.60 8.48 0 6 21.5963.70 3.66 2.32 7 19.35 59.69 3.65 1.50 400 rpm 0 0 0 0 0 300 1.3 7.094.21 0 21.16 >150 3 16.07 80.01 3.41 22.43 48.70 4 9.56 92.08 3.88 11.040 4.3 7.16 94.70 3.94 4.57 0 5 4.08 86.30 3.68 1.31 0 650 rpm 0 0 0 0 0300 2 18.01 89.13 4.13 6.57 112.57 3 30.72 145.67 6.86 1.61 4.31 4 16.02129.69 6.59 1.39 0 5 12.65 147.54 6.87 0

Example 5. Bioreactor Culture of Moniliella in a 400 L Bioreactor

It was found that the oxygen transfer rate was a key factor inerythritol production in the 400 L bioreactor. Two dip tubes were usedto increase the turbulence, an air sparger was installed in the bottomof the vessel, and the aspect ratio was increased. The results (in g/L)are shown in the table below.

Table 4. Production of Erythritol and Other Products in a 400 LBioreactor

TABLE 4 Production of Erythritol and Other Products in a 400 LBioreactor Day Glycerol Erythritol Ribitol Ethanol 0 0 0 0 0 1 6.1 9.21.5 15.3 2 10.0 60.3 1.7 19.3 3 11.8 75.3 0 27.7

Example 6. Purification of Saccharification Product

Corn cob was saccharified and the resulting sugar mixture purified byion exchange. Cation exchange and anion exchange were used to remove themetal components listed in the table below.

Table 5. Metal elements in ppm in solution of saccharified corn cobcontaining 100 g/L glucose, before and after ion exchange.

TABLE 5 Metal elements in ppm in solution of saccharified corn cobcontaining 100 g/L glucose, before and after ion exchange. Before ionAfter cation After cation and Element exchange exchange anion exchangeMn 9 0 0 Zn 9 0 0 Si 71 70 0 Fe 14 0 0 P 668 704 0 K 4951 20 0 Mg 418 00 Na 10099 0 0 Ca 342 0 0 S 2048 2372 37

The purified saccharified corn cob solution was then used for erythritolproduction by two different Moiliella strains, CBS 461.67 (Monillielapollinis) and CBS 567.85 (Moliniella megachiliensis). Flask cultureswere used, and the media components included 10 g/L yeast extract, 1 g/Lpotassium nitrate, 0.3 g/L phytic acid, 2 mg/L of cupric sulfate as wellas purified saccharified corncob. Glucose was consumed in 2 days andlittle xylose was consumed.

TABLE 6 Erythritol production by two different strains from purifiedsaccharified corn cob containing 160 g/glucose and 140 g/L xylose. DayGlycerol Erythritol Ribitol Ethanol Fructose Strain CBS 461.67 0 6.854.54 0 0.36 9.78 2 9.22 31.20 0 22.35 0 3 7.30 33.46 0 19.80 0 StrainCBS 567.85 0 0 4.54 0 0.21 10.30 2 9.72 29.36 0 22.52 0 3 7.82 45.99 019.47 0

Erythritol production yield was 21% in CBS 461.67 and 28% in CBS 567.85.This yield is comparable to the erythritol production with reagent gradeglucose (30 to 40% yield).

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

While this invention has been particularly shown and described withreferences to preferred embodiments thereof, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the scope of the inventionencompassed by the appended claims.

1.-26. (canceled)
 27. A method for making sugar alcohols, the methodcomprising: combining cellulosic or lignocellulosic biomass thatcontains one or more sugars with a microorganism, the recalcitrance ofthe biomass having been reduced by bombardment with electrons; andutilizing jet mixing agitating while maintaining themicroorganism-biomass combination under conditions that enable themicroorganism to ferment at least one of the sugars to a sugar alcohol,wherein said conditions comprise utilizing a jet mixer while spargingair into the combination at 0.3 to 1 VVM to provide a dissolved oxygenlevel above 10%, and wherein said sugar alcohol is erythritol and themicroorganism is a species of Moniliella.
 28. The method of claim 27,further comprising saccharifying the cellulosic or lignocellulosicbiomass.
 29. The method of claim 27, wherein the microorganism is M.megachiliensis.
 30. The method of claim 27, wherein the cellulosic orlignocellulosic biomass is selected from the group consisting of: paper,paper products, paper waste, paper pulp, pigmented papers, loadedpapers, coated papers, filled papers, magazines, printed matter, printerpaper, polycoated paper, card stock, cardboard, paperboard, cotton,wood, particle board, forestry wastes, sawdust, aspen wood, wood chips,grasses, switchgrass, miscanthus, cord grass, reed canary grass, grainresidues, rice hulls, oat hulls, wheat chaff, barley hulls, agriculturalwaste, silage, canola straw, wheat straw, barley straw, oat straw, ricestraw, jute, hemp, flax, bamboo, sisal, abaca, corn cobs, corn stover,soybean stover, corn fiber, alfalfa, hay, coconut hair, sugar processingresidues, bagasse, beet pulp, agave bagasse, algae, seaweed, manure,sewage, offal, agricultural or industrial waste, arracacha, buckwheat,banana, barley, cassava, kudzu, oca, sago, sorghum, potato, sweetpotato, taro, yams, beans, favas, lentils, peas, and mixtures of any ofthese.
 31. The method of claim 27, where the recalcitrance of thebiomass has been additionally reduced by a treatment method selectedfrom the group consisting of: sonication, oxidation, pyrolysis, steamexplosion, chemical treatment, and mechanical treatment.
 32. The methodof claim 27, further comprising mechanically treating the cellulosic orlignocellulosic biomass to reduce its bulk density and/or increase itssurface area.
 33. The method of claim 27, wherein the cellulosic orlignocellulosic biomass is comminuted.
 34. The method of claim 27,further comprising separating the one or more of the one or more sugarsprior to combining the cellulosic or lignocellulosic biomass with themicroorganism.
 35. The method of claim 27, further comprisingconcentrating the one or more sugars prior to combining the cellulosicor lignocellulosic biomass with the microorganism.
 36. The method ofclaim 28, wherein the saccharified biomass is adjusted to have aninitial glucose concentration of at least 5 wt %.
 37. The method ofclaim 27, further comprising culturing the microorganism in a cellgrowth phase before combining the cellulosic or lignocellulosic biomasswith the microorganism.
 38. The method of claim 28, further comprisingpurifying the biomass.
 39. The method of claim 38, wherein saidpurifying comprises removing metal ions.
 40. The method of claim 27,wherein the microorganism is M. pollinis.
 41. The method of claim 40,wherein the wherein the microorganism is M. pollinis strain CBS 461.67.42. The method of claim 29, wherein the microorganism is M.megachiliensis strain CBS 567.85.
 43. The method of claim 28, whereinone or more cellulases saccharify the cellulosic or lignocellulosicbiomass.
 44. The method of claim 33, wherein the cellulosic orlignocellulosic biomass is comminuted via dry milling or wet milling.